Block diagram of the Oscillatom’s three interconnected subsystems. In the upper section, the atomic frequency standard consists of a quartz generator (G1), a frequency multiplier, a Varian BLR-2 cesium-beam tube and an electronic servo system that locks the generator to the cesium resonance. Its 6305 kHz output controls the clock shown below. In this second section, a digital comparator steers a separate 5 MHz quartz generator (G2), with an adjustable nominal offset. Frequency dividers and output amplifiers supply selectable signals at 5 MHz, 1 MHz and 100 kHz, together with one-second pulses and a visual time display. The power-supply and reserve unit at right serves both sections and maintains operation during an interruption of the external power supply.